General. Analytical HPLC was performed on a Spectra-Physics 8100/4000 liquid chromatograph using 7-34% acetonitrile in 0.01 M KHzP04 buffer (pH 3.2) and detection at 220 nm. A Beckman Ultrasphere ODS column (4.6 X 150 mm, at flow rate 1.5 mL/min) was used for the analytical runs. Preparative HPLC was carried out on a Whatman Magnum 20 (PartisillO/ODS-3) column hooked up to an Eldex pump by running step gradient of 0-16% acetonitrile in 0.01 M KH2POI buffer (pH 6.0) at flow rate of 25 mL/min. Mass spectra were obtained with a VG Analytical ZAB-1F mass spectrometer equipped with a high-field magnet and operated in the fast-atom-bombardment mode with thioglycerol-oxalic acid matrix.A Representative Reductive Dechlorination. A solution of aridicin aglycon (1, 210 mg) in 100 mL of distilled water (pH adjusted to 8.1 with dilute ",OH) was hydrogenated in a Parr hydrogenator over Pd/C (lo%, 200 mg) at 60 psi H2 and room temperature. Progress of the dechlorination was monitored by taking samples, filtering through Celite, and directly analyzing by HPLC as described above. After 140 min, all starting material disappeared, and the catalyst was removed by filtration through Celite (Aldrich). Lyophylization of the filtrate gave ca. 167 mg of powder, from which the following products were isolated through preparative HPLC: 2 [20 mg; t, 12.86 min; FAB-MS, m/z 1262 (MH+)]; 3 [lo mg; t, 12.22 min; FAB-MS, m/z 1228 (MH+)]; 4 [27 mg; t, 11.08 min; FAB-MS, m/z 1228 (MH+)]; 5 [52 mg; t, During the course of our study on selenium-assisted carbonylation with carbon monoxide,' we have found that (1) (a) Sonoda, N.; Yasuhara, T.; Kondo, K.; Ikeda, T.; Tsutsumi, S. J. Am. Chem. SOC. 1971, 93, 6344. (b) Intramolecular aminolysis of selenol carbamate intermediates gives cyclic ureas in good yields: Yoshida, T.; Kambe, N.; Murai, S.; Sonoda, N. TetrahedronLett. 1986,27, 3077. (c) Kondo, K.; Takarada, M.; Murai, S.; Sonoda, N. Synthesis 1979, 597.